The invention concerns a process for the demagnetization or for the magnetic calibration of parts of ferromagnetic materials, in particular for the demagnetization or calibration of permanent magnets, as well as for the demagnetization of components that have been exposed to a magnetic field during processing and have retained a residual magnetism from it, for example parts that have been ground on magnetic clamping plates, or chucks, or parts that are to be totally free of residual magnetism, such as ball bearings.
A known demagnetizing process consists of exposing such parts to an alternating magnetic field of decreasing intensity, for example to conduct them through the field of an AC-powered coil or to expose them within a coil to the decreasing alternating field of a periodic capacitor discharge.
These known processes cause severe heating of the field coil when in continuous operation. The capacitor-discharge process is not continuous one and hence is difficult to automate.
Both processes suffer from the fact that for the production of a high demagnetizing field intensity in a coil, the latter absorbs a high reactive current. If this is compensated in the known manner by means of a series- or parallel-connected capacitor, then the resonant frequency at which the current maximum appears is dependent on the quantity and type of parts inserted into the coil. In addition, the intended compensation is made more difficult by the variation of the capacitance of the connected capacitor resulting from warming during operation and by its variation in time. The invention avoids these deficiencies.